1. Field of the Invention
This invention is related to LED Light Extraction and white LED with high luminous efficacy for optoelectronic applications, and, more specifically, relates to a textured phosphor conversion layer LED.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification. A list of these different publications can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)
In conventional white LEDs, the phosphor conversion layer is typically placed directly on top of the blue GaN chip. The surface is usually smooth and conformal to the surface of the GaN chip. The blue photons from the GaN chip are down converted into photons of lower energy (Yellow, Green, and Red) in the phosphor conversion layer. A large fraction of these photons are internal reflected in the phosphor conversion layer and directed back toward the chip where they are reabsorbed. This results in a decrease in overall luminous efficiency.
Previous applications of the phosphor conversion layer are limited to placing a gel or other liquid form of material onto the chip, and allowing the phosphor to cure. This non-uniform and typically smooth application of the phosphor does not take into account several factors that can be used to increase the efficiency of the LED.